A Virginia energy panel, apparently responding to protests from central and Northern Virginia, has postponed a controversial vote on lifting the state's moratorium on uranium mining.

The delay could deal a setback to the Marline Uranium Corp., a New York-based corporation that has invested more than $25 million in hopes of turning Virginia into the first uranium-producing state east of the Mississippi River.

The chairman of the state Coal and Energy Commission's uranium subcommittee reversed himself today and said it was unlikely that the panel will present legislation for uranium mining in time for the 1983 General Assembly session.

"We're not going to rush into doing anything, we're not rushing to meet any deadlines," said state Sen. Daniel W. Bird (D-Wytheville) after a subcommittee meeting. "We have a very small staff and we have a lot of scientific data to digest."

Another member of Bird's panel said the new "go slow" approach had been forced by public criticism of uranium mining, particularly from Northern Virginia officials. "It's called politics," said State Sen. Frederick C. Boucher (D-Abingdon), the panel's leading advocate of extending the mining moratorium.

"The people who are directly involved in this are from the most populous parts of the state," Boucher said. "In Northern Virginia alone, you've got virtually one-fourth of the votes in the General Assembly" which would probably go against any mining measure.

Fairfax County Board Chairman John F. Herrity has led the fight in the Washington suburbs, charging that mining operations in central Virginia could expose the Occoquan Reservoir to radioactive leakage, contaminating Fairfax's water supply.

The moratorium is scheduled to expire July 1, but Boucher predicted that, if no recommendation is forthcoming from the subcommittee, the legislature will extend it next January.

In an effort to overcome the legislative obstacles, Marline recently added to its lobbying forces by retaining former Democratic congressman Thomas Downing of Newport News and the law firm of real estate developer John T. (Til) Hazel, Jr. of Fairfax to present its case to local officials.

Marline vice president Norman Reynolds said that a delay would be a serious setback for the company.